Prolonged sitting, reclining or laying in the same position is known to present issues that can be harmful, such as bedsores, ulcers and issues relating to blood circulation, such as blood clots. In many instances, however, people are subjected to prolonged periods of inactivity due to age, infirmity, illness, surgery or other conditions. People who may be prone to these prolonged periods in a single position, such as sitting in a wheel chair or laying in a hospital bed may need to be alerted after a certain amount of time to stand or move about to prevent the formation of bedsores, ulcers, blood clots or similar issues.
There have been previous attempts to develop devices to warn patients of prolonged periods without movement. One such device is described in U.S. Pat. No. 4,554,930 issued on Nov. 26, 1985 to Kress. Kress measures the pressure on a patient's skin and then warns the patient before the pressure has been applied long enough to cause damage to the skin. Another device is described in U.S. Pat. No. 7,504,955 issued on Mar. 17, 2009 to Overturf. It also detects the pressure applied by a user to a particular area and warns the user when the pressure has been applied for a predetermined amount of time. Overturf further includes a mechanism to alter the inclination of the patient, thus changing the relative pressure points.
These and other prior art devices suffer from a number of deficiencies. First, in order to ensure that potential injuries or issues are avoided from prolonged periods of pressure, the patient or user needs to keep the pressure removed from the affected area for a minimum amount of time. Reapplication of the pressure too soon to the affected area can have deleterious affects. None of the prior art devices monitor the length of time the patient or user has stayed off of the relevant pressure points and none are able to warn the patient if they sit or lay down too quickly after getting up. Further, the prior art devices are unable to account for patients who get up before being warned. The prior art devices work on fixed cycles and are unable to adjust their operation to account for patients moving before they have been warned by the device.